After sunset, Space Shuttle Atlantis is bathed in light from the fixed service structure on Launch Pad 39B. Seen on either side of Atlantis’ engine nozzles are the tail masts, which provide several umbilical connections to the orbiter, including a liquid-oxygen line through one and a liquid-hydrogen line through another. Below the mobile launcher platform, on which Atlantis rests, is the crawler-transporter beginning to move away from the platform. Image credit: NASA / Kim Shiflett, 08/29/2006.

At the launch readiness news conference on Monday afternoon, Wayne Hale, shuttle program manager, said that even though the tropical weather put them behind earlier in the week, thanks to hard work by the launch team, the vehicle is ready for liftoff and “we are looking forward to a really good mission.”

LeRoy Cain, launch integration manager, reported that after reviews by the mission management team, “At the end of the day we did our readiness poll to continue from here toward launch and we got a “go” from all the elements and we feel like we’re in very good shape.”

Shuttle Launch Director Mike Leinbach said the countdown is going smoothly and they are looking for a good, on-time liftoff on Wednesday.

U.S. Air Force First Lt. Kaleb Nordgren of the 45th Weather Squadron at Cape Canaveral Air Force Station provided an update on the prospects for launch-day weather issues. Conditions continue to look favorable, with only a 20 percent chance of a “no go” due to weather at the liftoff time of 12:29 p.m.

The countdown officially began at 8 a.m. Sunday, at the T-43 hour mark, which includes over 30 hours of built-in hold time prior to a targeted 12:29 p.m. launch on Wednesday. The launch time is the middle point in the launch window that extends for 10 minutes.

Source: NASA

Coverage of the STS-115 launch begins Wednesday morning, September 6th at 6:30 AM EDT on NASA TV.

For those with HDTV service, HDNet will begin coverage of the launch at 8:00 AM EDT, and will be the only network covering Atlantis’ launch in high definition format. (I’ve just upgraded to HDTV and cannot wait for this broadcast.)

For an overview of this Shuttle mission to the International Space Station and a breakdown of day-by-day events, view this interactive feature.